Field
Aspects of the present disclosure are directed to a window assembly, and more particularly to a mulling system for a window assembly.
Description of the Related Art
Windows include window frames which are typically made from wood, metal, polymers, or a variety of combinations of these materials. A mullion, or mull, is commonly used to connect adjacent window frames together to form a window assembly. Although such a window assembly may enable a larger building opening to be filled by windows, the size and arrangement of a window assembly is limited because it must withstand wind loads and water infiltration (e.g., leaking) design requirements established by building codes, ordinances, and industry standards, such as those developed by the American Architectural Manufacturers Association (AAMA).
Traditionally, window frames are joined into an assembly in the field (e.g., field mulled) using an H-mull mulling system. The H-mull is typically formed of a vinyl or polymeric material and has a generally H-shaped cross-section defined by a central portion and lineals centered at either end. The H-mull is secured to the building and spans across the building opening, and adjacent window frames are positioned to abut the respective sides of the central portion of the H-mull. Screws are used to secure the adjacent window frames to one another through the mullion. Caulking or other sealant is often applied excessively to fill voids left between the H-mull and window frames in an attempt to prevent water from infiltrating the mullion and leaking into the adjacent building wall or interior space. Wood, metal, or plastic reinforcement may be attached to the central portion of the H-mull in order to increase the strength and rigidity of the window assembly. High-strength screws or other fasteners are then used to secure the outer perimeter of the window frames of the completed window assembly to the building opening.
These and other mulling systems known in the art are inadequate for several reasons. For example, mulling systems known in the art rely primarily on caulking to prevent water leakage, but improper field mulling, installation, and/or handling of the window assembly often breaks or deforms the caulk seal or mullion and enables water to infiltrate the mullion and leak into the adjacent building wall or interior space. The screws securing one window frame to another penetrate the H-mull, creating additional potential leak points that require sealing.
In addition, these mulling systems are commonly installed in the field where they offer the installer significant judgment regarding the type and placement of screws and caulking to use in forming the window assembly, which leads to inconsistent performance of each mulling system and necessitates costly and time consuming site testing of each window assembly. Further, these known mulling systems typically include a thin vinyl mullion with very little rigidity that often requires reinforcement to meet applicable wind load and other design requirements.